These two images of Jupiter's small, irregularly shaped
moon Amalthea, obtained by the camera onboard NASA's Galileo
spacecraft in August 1999 (left) and November 1999
(right), form a 'stereo pair' that helps scientists determine
this moon's shape and the topography of its surface features.
Features as small as 3.8 kilometers (2.4 miles) across can
be resolved in these images, making them among the
highest-resolution images ever taken of Amalthea.

The large impact crater visible in both images, near the
right-hand edge of Amalthea's disk, is about 40 kilometers
(about 29 miles) across; two ridges, tall enough to cast
shadows, extend from the top of the crater in a V-shape
reminiscent of a 'rabbit ears' television antenna. To the
left of these ridges, in the top center portion of Amalthea's disk, is
a second large impact crater similar in size to the first
crater. To the left of this second crater is a linear 'streak'
of relatively bright material about 50 kilometers (31 miles) long. In
previous spacecraft images of Amalthea taken from other viewing
directions, this bright feature was thought to be a small, round,
bright 'spot' and was given the name Ida. These
new images reveal for the first time that Ida is actually a
long, linear 'streak.' This bright streak may represent material
ejected during the formation of the adjacent impact crater,
or it may just mark the crest of a local ridge. Other patches
of relatively bright material can be seen elsewhere on Amalthea's
disk, although none of these other bright spots has
Ida's linear shape.

In both images, sunlight is coming from the left and north is
approximately up. Note that the north pole of Amalthea is missing
in the right-hand image (it was cut off by the edge of
the camera frame). The bright streak, Ida, is on the side of the
mooon that faces permanently away from Jupiter, and the crater
near the right-hand edge of the disk is in the center
of Amalthea's leading side (the side of the moon that 'leads' as
Amalthea moves in its orbit around Jupiter).

The images are, from left to right: Amalthea taken on August 12,
1999 at a range of 446,000 kilometers (about 277,000 miles) and
on November 26, 1999 at a range of
374,000 kilometers (about 232,000 miles).